Recently, there has been increasing popularity of 110 size cameras. The photographic enlargement prints obtained from the small 110 picture image does not have the same graininess and resolving power as those of a print obtained by enlarging from a large-sized picture image.
The graininess of a color image can be improved by increasing the number of silver halide grains and diffusing dyes formed by color development as described in T. H. James, "Theory of the Photographic Process", 4th Edition, pages 620-621. However, attempts at increasing the number of silver halide grains while maintaining a high photographic sensitivity requires an increase in the amount of coated silver and causes a reduction in resolving power due to the increased amount of silver as well as other disadvantages relating to cost and other photographic properties.
Attempts at improving graininess by diffusion of dyes improves the rms (root mean square) granularity by using so-called dye diffusible type couplers as described in British Pat. No. 2,080,640A but this method gives an unpleasant visual sensation as described later.
The inventors have made various investigations with respect to improving graininess and have found the following. When a non-diffusible type coupler forms a properly smearing diffusible coupler (hereinafter, the non-diffusible type coupler is referred to as a dye diffusible type coupler), the so-called rms granularity (the rms granularity is described in T. H. James; "Theory of the Photographic Process"; 4th Edition, page 619) is greatly improved. However, the positioning and development probability of silver halide particles occur in random course, the dye diffuses to smear and mixes with the neighboring dye or dyes, whereby the overlap of dye clouds becomes larger thus randomly forming huge dye clouds. This is visually very unpleasant and the visual sensation of graininess is sometimes deteriorated.